Hollow shaft blank plate forging forming method and die with outboard flange feature

Abstract

The present application belongs to the field of advanced forming manufacturing and plastic processing, and provides a hollow shaft blank plate forging forming die with an outer flange feature, comprising an upper die holder, a shearing and extruding punch, a floating female die, a floating mandrel, an outer female die, a ejector rod, a nitrogen spring, a backing plate, and a lower die holder. The present application also provides a method for forming a hollow shaft blank plate with an outer flange feature, which utilizes the above-mentioned hollow shaft blank plate forging forming die with an outer flange feature, and comprises the following steps: Step 1, obtaining a pipe material that meets the required part size; Step 2, forming a blank with the required part shape with an outer flange feature by using the above-mentioned die; and Step 3, performing a first machining on the hollow shaft blank to form a hollow shaft. The method realizes the application of plate forging technology on hollow shafts, greatly reduces the forming load, reduces the manufacturing cost, and improves the service life of the forming die and the core competitiveness of the product under the premise of meeting the performance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metal plastic forming, in particular to a hollow shaft blank plate forging forming method and die with an outer flange feature. BACKGROUND

[0002] With the rapid development of new energy vehicles, due to the limitation of the endurance mileage, the weight of automobile parts such as motor shaft must be reduced, and the solid shaft on the traditional automobile has already been unable to meet the requirements of automobile lightweight manufacturing, so the hollow shaft is born. The characteristics of such hollow shaft are that the height-diameter ratio is greater than or equal to 2, the wall thickness of the middle part is less than or equal to 10mm, and the shaft has an outer flange feature at one end.

[0003] At present, people generally adopt machining, rotary forging and traditional cold forging methods to form the hollow motor shaft with the outer flange feature, but the machining allowance is large, especially for such hollow shaft with the outer flange feature, not only the inner wall needs to be drilled, but also the outer wall needs to be machined when forming the outer flange, the material utilization rate is low, the cost is high, and the product has no competitive advantage; the rotary forging equipment occupies a large area and is expensive, which is not suitable for small batch production; the traditional cold forging method has large forming force, low die life, and is easy to produce defects such as folding and cracking.

[0004] Therefore, how to change the present situation that the hollow shaft blank with the outer flange feature is difficult to form in the prior art has become a problem to be solved by the person skilled in the art. SUMMARY

[0005] The purpose of the present application is to provide a hollow shaft blank plate forging forming die with an outer flange feature to solve the problems existing in the prior art and improve the competitive advantage of the existing product.

[0006] To achieve the above-mentioned purpose, the present application provides the following scheme: the present application provides a hollow shaft blank plate forging forming die with an outer flange feature, which comprises an upper die seat, a shearing and extruding punch, a floating die, a floating mandrel, an outer die, a ejector rod, a nitrogen spring, a backing plate, a lower die seat, the shearing and extruding punch, the floating die, the outer die, the ejector rod, the backing plate and the floating mandrel are coaxially placed between the upper and lower die seats, the nitrogen springs are uniformly distributed on the outer die to ensure that the floating die is in force balance, the floating die and the outer die are connected by the nitrogen spring, the bottom of the outer die and the floating mandrel slide against each other, the floating die and the outer die are connected by sliding, wherein the outer die and the floating mandrel have a gap, the lower end gap ensures relative sliding, and the upper end gap ensures the wall thickness of the pipe, the shearing and extruding punch has a gap between the outer die and the floating mandrel, the ejector rod has a gap between the lower die seat and the backing plate, the nitrogen spring is a limiting element of the floating die, the limiting element of the shearing and extruding punch is a limiting block on the press, and the connecting and positioning elements are screws and pins.

[0007] Preferably, the floating mandrel upper end working part radius should be between 0.1mm and 5mm.

[0008] Preferably, the minimum height between the shear extrusion punch and the floating die should be greater than the target part outer flange height.

[0009] The present application also provides a hollow shaft blank plate forging forming method with an outer flange feature, which utilizes the above-mentioned hollow shaft blank plate forging forming die with an outer flange feature, and comprises the following steps:

[0010] Step one: obtaining a pipe material meeting the required part size;

[0011] Step two: forming a blank with the required part outer shape with an outer flange feature by utilizing the above-mentioned die;

[0012] Step three: once machining the hollow shaft blank to form a hollow shaft.

[0013] Preferably, in the step one, the pipe material meeting the required part should first include drilling, turning or drawing to ensure uniform wall thickness, and the height-diameter ratio of the pipe material should be greater than 2:1.

[0014] Preferably, in the step two, the stroke of the shear extrusion punch should be greater than the maximum relative distance between the floating die and the outer die.

[0015] The present application has the following technical effects compared with the prior art: the present application provides a hollow shaft blank plate forging forming die with an outer flange feature, which comprises an upper die holder, a shear extrusion punch, a floating die, a floating mandrel, an outer die, a ejector rod, a nitrogen spring, a backing plate, and a lower die holder. The shear extrusion punch, the floating die, the outer die, the ejector rod, the backing plate, and the floating mandrel are coaxially placed between the upper and lower die holders. The nitrogen springs are evenly distributed on the outer die to ensure that the floating die is in force balance. The floating die and the outer die are connected by the nitrogen springs. The bottom of the outer die and the floating mandrel slide against each other. The floating die and the outer die slide against each other. There is a gap between the outer die and the floating mandrel. The lower end gap ensures relative sliding, and the upper end gap ensures the wall thickness of the pipe material. There is a gap between the shear extrusion punch and the outer die and the floating mandrel. There is a gap between the ejector rod and the lower die holder and the backing plate. The nitrogen springs are the limiting elements of the floating die. The limiting elements of the shear extrusion punch are the limiting blocks on the press. The connecting and positioning elements are screws and pins. The present application also provides a hollow shaft blank plate forging forming method with an outer flange feature. The first step is to obtain a pipe material meeting the required part. The second step is to place the machined part in the above-mentioned die to form the required part shape with an outer flange feature. The third step is to once machine the hollow shaft blank to form a hollow shaft. The present application also has the following advantages:

[0016] (1) By adopting the above process steps, the required hollow shaft can be processed and manufactured, that is, the wall thickness, height-diameter ratio, and diameter and height of the outer flange of the pipe blank all meet the requirements of the hollow shaft, and compared with the traditional processing process, the processing process of the part is greatly reduced during processing, the processing efficiency is provided, the processing cycle is shortened, the utilization rate of the related materials is improved, the processing cost is saved, and the product competitiveness is improved.

[0017] (2) The hollow shaft with an outer flange feature can be produced through the above process steps, and the mechanical properties and other indicators can meet the requirements of the parts produced by the traditional forging and pressing method, especially the flange area is deformed by shearing and extruding, and the strength meets the characteristics of the hollow shaft that can withstand high speed and alternating load.

[0018] (3) The folding defects formed in the nitrogen spring stroke during the forming process can be effectively improved by using the mold to form the hollow shaft blank after preliminary processing, and the number and tonnage of nitrogen springs required can be directly reduced. Since the contact area between the shearing and extruding punch and the pipe is small, the forming force is stable and much smaller than the forming force required by the traditional forging forming method, thereby greatly increasing the service life of the mold. The inner hole and outer circle of the formed part have high shape and position accuracy, and the inner hole after forming can be all machined without assembly requirements, thereby greatly saving the machining cost and improving the product competitiveness. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0020] Figure 1 It is a cross-sectional structure schematic diagram of the working of the hollow shaft blank plate forging and forming mold with an outer flange feature of the present application;

[0021] Figure 2 It is a cross-sectional structure schematic diagram of the pipe required in step one of the forging and forming method of the hollow shaft blank plate with an outer flange feature of the present application;

[0022] Figure 3 It is a cross-sectional structure schematic diagram of the hollow shaft blank after forming by using the mold in step two of the forging and forming method of the hollow shaft blank plate with an outer flange feature of the present application;

[0023] Figure 4 It is a cross-sectional structure schematic diagram of the hollow shaft blank after machining in step three of the forging and forming method of the hollow shaft blank plate with an outer flange feature of the present application;

[0024] Wherein 1, 2, 3, 4, 5, 6, 7, 8, 9 are upper die holder, shear-extrusion punch, floating die, floating mandrel, outer die, ejector pin, nitrogen spring, backing plate, lower die holder respectively; D is the outer diameter of the pipe material required in step one, H is the height of the pipe material, L is the wall thickness of the pipe material; H1 is the lowest height between the shear-extrusion punch and the floating die in step two, L1 is the shear-in depth of the shear-extrusion punch, r is the fillet radius of the lower end of the inner wall of the shear-extrusion punch; H2 is the height of the outer flange of the target part in step three; t1, t2 are two different thicknesses of the side wall of the end of the target part. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application.

[0026] The present application aims to provide a hollow shaft blank plate forging forming die with an outer flange feature to solve the problems in the prior art and improve the competitiveness of existing products.

[0027] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the present application will be further described in detail below with reference to the drawings and specific embodiments.

[0028] Please refer to Figures 1-4 , wherein, Figure 1 is a cross-sectional structure schematic diagram of a hollow shaft blank plate forging forming die with an outer flange feature of the present application in working, Figure 2 is a cross-sectional structure schematic diagram of a pipe material required in step one of a hollow shaft blank plate forging forming method of the present application, Figure 3 is a cross-sectional structure schematic diagram of a hollow shaft blank after forming by using a die in step two of a hollow shaft blank plate forging forming method of the present application, Figure 4 is a cross-sectional structure schematic diagram of a hollow shaft blank after machining in step three of a hollow shaft blank plate forging forming method of the present application.

[0029] The application provides a hollow shaft blank plate forging forming die with an outer flange feature, comprising an upper die seat 1, a shearing and extruding punch 2, a floating female die 3, a floating mandrel 4, an outer female die 5, a ejector rod 6, a nitrogen spring 7, a backing plate 8, and a lower die seat 9, wherein the shearing and extruding punch 2, the floating female die 3, the floating mandrel 4, the outer female die 5, the ejector rod 6 and the backing plate 8 are coaxially arranged between the upper die seat 1 and the lower die seat 2, the nitrogen springs 7 are uniformly arranged on the lower die seat 9 to ensure that the floating female die 3 is balanced under force, the floating female die 3 is arranged on the nitrogen spring 7, the ejector rod 6 is arranged in the backing plate 8, the floating mandrel 4 is arranged on the top of the backing plate 8, and the floating female die 3 is slidably connected with the outer female die 5, wherein gaps are formed between the floating female die 3 and the floating mandrel 4, the lower end gap ensures relative sliding, and the upper end gap ensures the wall thickness of the pipe, gaps are formed between the shearing and extruding punch 2 and the outer female die 5 and the floating mandrel 4, gaps are formed between the ejector rod 6 and the lower die seat 9 and the backing plate 8, the nitrogen spring 7 is a limiting element of the floating female die 3, the limiting element of the shearing and extruding punch 2 is a limiting block on the press, and the connecting and positioning elements are screws and pins.

[0030] In addition, the round corner radius of the upper end working part of the floating female die 3 should be between 0.1 mm and 5 mm, and the minimum height H1 between the shearing and extruding punch 2 and the floating female die 3 should be greater than the height H2 of the outer flange of the target part.

[0031] The application also provides a hollow shaft blank plate forging forming method with an outer flange feature, which utilizes the hollow shaft blank plate forging forming die with an outer flange feature and comprises the following steps.

[0032] Step one: obtaining a pipe material meeting the requirements of a target part,

[0033] Step two: forming a blank with the shape of the target part with an outer flange feature by using the die,

[0034] Step three: performing one machining on the hollow shaft blank to form a hollow shaft.

[0035] Specifically, in step one, the step of obtaining a pipe material meeting the shape requirements of a target part comprises the following steps: extruding or drawing an original bar, and testing the chemical composition, structure, mechanical properties and defects of the material, verifying whether the pipe material after extruding or drawing and heat treatment meets the requirements of the target part, selecting the required pipe material according to the verification result, and ensuring that the height-diameter ratio H / D of the pipe material is greater than or equal to 2:1.

[0036] In step two, the blank with the required part shape with the outer flange feature is formed by using the above-mentioned mold, specifically comprising the following steps: positioning according to the outer side die 5 and the floating core 4 during forming, nitrogen spring 7 is uniformly distributed on the outer side die 5, the floating die 3 is placed above the spring 7 and can slide relative to the outer side die 5, then the blank is placed on the floating core 4, the cylinder pushes the shear extrusion punch 2 downward to form the part; the part is pushed out by the floating core 4 pushed by the ejector rod after forming. The one-sided gap between the pipe and the floating die 3 and the floating core 4 should be between 0.05mm and 0.1mm, the stroke of the shear extrusion punch 2 should be greater than the maximum relative distance of the floating die 3 and the outer side die 5, and the whole process uses a single cylinder press, which is simple in equipment, less in process, suitable for mass production, and has strong product competitive advantage.

[0037] In step three, the hollow shaft blank is machined once to form a hollow shaft, which should include machining the outer flange area, and can also include machining the inner wall, outer circle, step, relief groove or / and spline, etc.

[0038] The present application proposes a kind of hollow shaft blank plate forging forming method and mold with outer flange feature, with the following advantages:

[0039] (1) By using the above process steps, the required hollow shaft can be processed and manufactured, i.e. the wall thickness, height-diameter ratio of the pipe blank and the diameter and height of the outer flange and the tolerance all meet the requirements of the hollow motor shaft, and compared with the traditional machining process, the above-mentioned process greatly reduces the machining process of the part during machining, improves the machining efficiency, shortens the machining cycle, improves the utilization rate of related materials, saves processing cost and improves product competitiveness.

[0040] (2) The above process steps can produce existing hollow shafts with partial outer flange features, and the mechanical properties and other indicators can meet the requirements of parts produced by traditional forging and pressing methods, especially the flange area is deformed by shearing and extruding, and the strength meets the characteristics of high speed and alternating load required by the hollow motor shaft.

[0041] (3) By initially processing the hollow shaft blank with the mold, the folding defects caused by the height of the nitrogen spring during the forming process can be effectively improved, and the number and tonnage of nitrogen springs required can be directly reduced. Since the contact area of the shear extrusion punch and the pipe is small, the forming force is stable and much smaller than the forming force required by the traditional forging forming method, which greatly increases the service life of the mold. The inner hole and outer circle of the formed part have high shape and position accuracy, and the inner hole after forming can be completely machined without assembly requirements, which greatly saves machining cost and improves product competitiveness.

[0042] The principles and implementation manners of the present application are described by using specific examples in the present application, and the above examples are only used for helping to understand the method of the present application and its core idea; meanwhile, for the general technical personnel in the art, according to the idea of the present application, the specific implementation manners and application ranges will be changed. In conclusion, the content of the present specification should not be understood as the limitation of the present application.

Claims

1. A method for forging a hollow shaft blank with an external flange feature, utilizing a forging die for a hollow shaft blank with an external flange feature to produce a hollow shaft blank with an external flange feature without folding or buckling defects, characterized in that: The mold comprises an upper die base, a shearing punch, a floating die, a floating mandrel, an outer die, a push rod, a nitrogen spring, a pad, and a lower die base, wherein the shearing punch, the floating die, the floating mandrel, the outer die, the push rod and the pad are all coaxially placed between the upper die base and the lower die base, the nitrogen springs are distributed on the lower die base, the floating die is placed on the nitrogen springs, the push rod is placed in the pad, the floating mandrel is placed on the top of the pad, the floating die is slidably connected to the outer die, wherein a gap is provided between the floating die and the floating mandrel, the gap at the lower end ensures relative sliding, and the gap at the upper end ensures the wall thickness of the pipe, the shearing punch has a gap with the outer die and the floating mandrel, the push rod has a gap with the lower die base and the pad, the nitrogen spring is a limiting element of the floating die, the limiting element of the shearing punch is a limiting block on the press, and the connecting and positioning elements are screws and pins; the forming method comprises the following steps: Step 1: Obtain pipes that meet the required parts; Step 2: using the above mold to form a blank with the required part shape and external flange features; Step 3: Machining the hollow shaft blank to form the hollow shaft.

2. The method for forging a hollow shaft blank with an external flange feature according to claim 1, characterized in that: The minimum height between the shearing punch and the floating die should be ensured to be greater than the height of the outer flange of the target part.

3. The method for forging a hollow shaft blank with an external flange feature according to claim 1, wherein: In step 1, the height-to-diameter ratio of the pipe is greater than 2:

1.

4. The method for forging a hollow shaft blank with an external flange feature according to claim 1, wherein: In the step 2, the stroke of the shearing punch should be greater than the maximum relative distance between the floating die and the outer die.

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